This invention relates to an electrolytic method and device for sterilizing water. The device of the invention essentially produces germicidal agents by low-voltage electrolysis of an electrolytic solution, such as a weak aqueous sodium chloride solution. The germicidal components are produced in solution and are directly mixed with the contaminated water.
Prior art water sterilization methods generally involve large centrally located facilities. Highly toxic chlorine gas is dissolved in water and this solution is mixed with the contaminated water. The use of free chlorine gas and a difficulty in dissolving the chlorine in the water are problems with utilizing this prior art technology.
An alternative to the use of free chlorine, in prior art water sterilization methods, is the use of sodium hypochlorite. Although sodium hypochlorite has a germicidal effect similar to free chlorine, it is less effective than chlorine and the water retains a significant chlorine odor due to the preservatives generally added to maintain the hypochlorite.
Other prior art methods for sterilizing water comprise the use of actinic radiations, such as an ultraviolet radiation source, placed near the contaminated water. Such methods are disclosed in U.S. Pat. No. 4,230,571 to Dadd, entitled OZONE/ULTRAVIOLET WATER PURIFICATION and U.S. Pat. No. 3,649,493 to Meiners, et al., entitled PROCESS OF PURIFYING WATER WITH ACTIVE HALOGEN COMPOUND AND ACTINIC RADIATIONS.
Conventional shipboard methods for sterilizing water include the use of bromine ion exchange resins and granular calcium hypochlorite. These methods are generally not effective in killing highly resistant microorganisms.
Recent developments in the prior art include the use of electrolysis to generate oxidants, which act as germicidal agents. One such electrolytic unit, manufactured by Oxidizers, Inc. (previously Ozone Technology Corporation) of Virginia Beach, Va., is reported to produce a gaseous mixture of ozone, chlorine, free radicals of oxygen and chlorine, and hydrogen peroxide. These gases are then introduced into the water to be treated. Since these gases are strong oxidants, they are very dangerous to work with. As previously noted, there also are technical difficulties associated with dissolving these gases into an aqueous medium. Other prior art electrolytic cells and systems which produce gaseous oxidants which are then introduced into the contaminated water are disclosed in: U.S. Pat. No. 4,555,323 to Collier, entitled CHLORINATION DEVICE; U.S. Pat. No. 4,308,117 to Sweeney, entitled GENERATION OF CHLORINE-CHLORINE DIOXIDE MIXTURES; and U.S. Pat. No. 4,236,992 to Themy, entitled HIGH VOLTAGE ELECTROLYTIC CELL.
In more recent developments in the prior art, electrolysis occurs in the aqueous medium, thereby removing the previously required step of dissolving the gases. Three prior art devices of this type are: Ster-O-Lizer.RTM. manufactured by Ster-O-Lizer Manufacturing Corp., Salt Lake City, Utah; Sanilec.RTM. Systems manufactured by Eltech Systems, Corp., Chandon, Ohio; and the device disclosed in U.S. Pat. No. 3,622,479 to Schneider, entitled METHOD FOR THE CONTINUOUS ELECTROLYTIC PRODUCTION OF CHLORINE FOR THE STERILIZATION OF WATER. Some of the oxidants that are produced by this method likely include: fresh nascent chlorine, ozone, hypochlorite and free radicals. However, all of these devices utilize the unseparated anode and cathode products as a sterilizing solution, thereby decreasing the germicidal effects. When the Ster-O-Lizer.RTM. and Sanilec.RTM. devices are used, the sterilizing solution is stored before introduction into the contaminated water, thereby allowing degradation of some of the oxidants contained in the solution. The '479 patent teaches fragmenting the electrolytic solution into electrically nonconducting drops before it is electrolyzed.
Prior art sterilization techniques are limited in their ability to treat certain pathogenic organisms. For example, Legionella pneumophilia and Giardia muris are two pathogenic organisms which are extremely resistant to prior art sterilization techniques.
Accordingly, it is a primary object of the present invention to provide a low-voltage method and device which provide increased germicidal effects over the prior art.
It is a further object of the present invention to provide a device which is inexpensive to manufacture, durable, compact, and easy to operate.
Other objects and further scope of applicability will become apparent from the detailed description to follow, along with the accompanying drawing.